While the wheels on the bus may go "round and round," data on a computer's bus goes up and down. Each bus inside a computer consists of set of wires that allow data to be passed back and forth. Most computers have several buses that transmit data to different parts of the machine. Each bus has a certain size, measured in bits (such as 32-bit or 64-bit), that determines how much data can travel across the bus at one time. Buses also have a certain speed, measured in megahertz, which determines how fast the data can travel. The computer's primary bus is called the frontside bus and connects the CPU to the rest of the components on the motherboard. Expansion buses, such as PCI and AGP, allow data to move to and from expansion cards, including video cards and other I/O devices. While there are several buses inside a computer, the speed of the frontside bus is the most important, as it determines how fast data can move in and out of the processor.

Stands for "Central Processing Unit." This is the pretty much the brain of your computer. It processes everything from basic instructions to complex functions. Any time something needs to be computed, it gets sent to the CPU. Every day, it's compute this, compute that -- you'd think the CPU would need a break after awhile. But no -- it just keeps on processing. The CPU can also be referred to simply as the "processor."

This interface is found on the back of older PCs and is used for connecting external devices such as printers or a scanners. It uses a 25-pin connector (DB-25) and is rather large compared to most new interfaces. The parallel port is sometimes called a Centronics interface, since Centronics was the company that designed the original parallel port standard. It is sometimes also referred to as a printer port because the printer is the device most commonly attached to the parallel port. The latest parallel port standard, which supports the same connectors as the Centronics interface, is called the Enhanced Parallel Port (EPP). This standard supports bi-directional communication and can transfer data up to ten times faster than the original Centronics port. However, since the parallel port is a rather dated technology, don't be surprised to see USB or Firewire interfaces completely replace parallel ports in the future.

The serial port is a type of connection on PCs that is used for peripherals such as mice, gaming controllers, modems, and older printers. It is sometimes called a COM port or an RS-232 port, which is its technical name. If that's not enough to confuse you, there are two types of serial ports -- DB9 and DB25. DB9 is a 9-pin connection, and DB25 is, you guessed it, a 25-pin connection. A serial port can only transmit one bit of data at a time, whereas a parallel port can transmit many bits at once. The serial port is typically the slowest port you'll find on a PC, if you find one at all. Most newer computers have replaced serial ports with much faster and more compatible USB ports.

Stands for "Small Computer System Interface," and is pronounced "scuzzy." SCSI is a computer interface that can be used to attach devices like hard drives and scanners to your computer. You can connect up to seven devices to a SCSI interface and still get good performance from all of them. SCSI can support faster data transfer rates than the other popular storage interface, IDE.

In telecommunications, RS-232 (Recommended Standard 232) is a standard for serial binary data signals connecting between a DTE (Data terminal equipment) and a DCE (Data Circuit-terminating Equipment). It is commonly used in computer serial ports.

Stands for "Universal Serial Bus." USB is the most common type of computer port used in today's computers. It can be used to connect keyboards, mice, game controllers, printers, scanners, digital cameras, and removable media drives, just to name a few. With the help of a few USB hubs, you can connect up to 127 peripherals to a single USB port and use them all at once (though that would require quite a bit of dexterity). USB is also faster than older ports, such as serial and parallel ports. The USB 1.1 specification supports data transfer rates of up to 12Mb/sec and USB 2.0 has a maximum transfer rate of 480 Mbps. Though USB was introduced in 1997, the technology didn't really take off until the introduction of the Apple iMac (in late 1998) which used USB ports exclusively. It is somewhat ironic, considering USB was created and designed by Intel, Compaq, Digital, and IBM. Over the past few years, USB has become a widely-used cross-platform interface for both Macs and PCs.

This high-speed interface has become a hot new standard for connecting peripherals (no pun intended). Created by Apple Computer in the mid-1990's, Firewire can be used to connect devices such as digital video cameras, hard drives, audio interfaces, and MP3 players, such as the Apple iPod, to your computer. A standard Firewire connection can transfer data at 400 Mbps, which is roughly 30 times faster than USB 1.1. This blazing speed allows for quick transfers of large video files, which is great for video-editing professionals. If 400 Mbps is still not fast enough, Apple Computer released new PowerMacs with Firewire 800 ports in early 2003. These ports support data transfer rates of 800 Mbps -- twice the speed of the original Firewire standard. You may see Firewire referred to by its technical name, IEEE 1394, since it was standardized by the Institute of Electrical and Electronics Engineers. Both terms refer to the same technology. If your computer doesn't have Firewire and you wish it did, fear not. As long as your computer has PCI slots, you can purchase a PCI Firewire card to add Firewire ports to your computer.

The hard drive is what stores all your data. It houses the hard disk, where all your files and folders are physically located. A typical hard drive is only slightly larger than your hand, yet can hold over 100 GB of data. The data is stored on a stack of disks that are mounted inside a solid encasement. These disks spin extremely fast (typically at either 5400 or 7200 RPM) so that data can be accessed immediately from anywhere on the drive. The data is stored on the hard drive magnetically, so it stays on the drive even after the power supply is turned off. The term "hard drive" is actually short for "hard disk drive." The term "hard disk" refers to the actual disks inside the drive. However, all three of these terms are usually seen as referring to the same thing -- the place where your data is stored. Since I use the term "hard drive" most often, that is the correct one to use.

Floppy disks have an interesting name, considering they do not appear to be "floppy." However, if you take the actual disk out of the protective casing, you will discover that the disk is, in fact, rather flexible. It is coated with iron oxide and stores data magnetically, just like a hard disk. The first floppy disks were created in 1969, the same year the Internet had its origin. These disks were 8 inches in diameter and were read-only, like a CD-ROM, meaning no data could be written to them by the user. The first 8 inch disks only held 80KB of data, but later versions could hold as much as 800KB. In 1978, a 5.25 inch disk was introduced, which could hold a whopping 360KB of data. Later revisions of the 5.25 inch floppy disk could store 1.2MB. These disks were used in early desktop PCs, such as the Apple IIe. In 1987, the 3.5 inch HD (high density) floppy disk was released, which could hold 1.44MB after being formatted. These disks were a little more durable than the 5.25 inch disks and were also more portable. For the next decade, the 3.5 inch floppy disk became the standard means of distributing commercial software titles and backing up personal data. In the late 1990s, CD-ROMs began to replace floppy disks as the standard means of distributing software. A few years later, consumers began migrating to recordable CDs for backing up their data. Apple's original iMac, released in 1998, was the first mainstream computer to not even include a floppy disk drive. While it took several years, many PC manufacturers eventually followed suit. Now most software is distributed on CDs and DVDs and most people back up their data either on recordable CDs or USB flash drives. Floppy disks are finally becoming a thing of the past, which is good, considering they are notorious for losing data. Still, the floppy disk will always have a special place in the hearts and minds of veteran computer users as it was the data storage medium many people grew up with.

Stands for "Compact Disc Read-Only Memory." A CD-ROM is a CD that can be read by a computer with an optical drive. The "ROM" part of the term means the data on the disc is "read-only," or cannot altered or erased. Because of this feature and their large capacity, CD-ROMs are a great media format for retail software. The first CD-ROMs could hold about 600 MB of data, but now they can hold up to 700 MB. CD-ROMs share the same technology as audio CDs, but they are formatted differently, allowing them to store many types of data.

Your computer's desktop is much like a physical desktop. You probably keep a number of commonly used items on your desk such as pens, papers, folders, and other items. Your computer's desktop serves the same purpose -- to give you easy access to items on your hard drive. It is common to store frequently used files, folders, and programs on your desktop. This allows you to access the items quickly instead of digging through the directories on your hard drive each time you want to open them. Both the Macintosh and Windows interfaces use the desktop as a central part of the interface. Both operating systems allow you to move items on and off the desktop as you wish and offer organization tools to arrange and clean up the items on the desktop. Yes, it would be nice if there was an option like that for a real-life desktop. You can also customize your computer's desktop with the pattern or background image of your choice.

Stands for "Single In-Line Memory Module." This is an older type of computer memory. A SIMM is a small circuit board with a bunch of memory chips on it. SIMMs use a 32-bit bus, which is not as wide as the 64-bit bus dual in-line memory modules (DIMMs) use. Newer processors require a 64-bit memory bus, so it is best to use DIMMs. Sometimes you can get away with installing SIMMS, but they have to be installed in pairs.

Stands for "Dual In-Line Memory Module." It is a type of computer memory. A DIMM is a small circuit board that holds memory chips. It uses a 64-bit bus to the memory, whereas a single in-line memory module (SIMM) only has a 32-bit path. This allows DIMMs to transfer more data at once. Because DIMMs have faster data transfer capabilities than SIMMs, they have pretty much replaced SIMMs.

Stands for "Random Access Memory," and is pronounced like the male sheep. RAM is made up of small memory chips that are connected to the motherboard of your computer. Every time you open a program, it gets loaded from the hard drive into the RAM. This is because reading data from the RAM is much faster than reading data from the hard drive. Running programs from the RAM of the computer allows them to function without any lag time. The more RAM your computer has, the more data can be loaded from the hard drive into the RAM, which can help speed up your computer. In fact, adding RAM can be more beneficial to your computer's performance than upgrading the CPU.

In a PC, the name assigned to the first serial port. The second is COM2, etc. PCs are typically designed to support up to four serial ports. On earlier PCs, two external serial ports were provided to connect a mouse and modem. On newer PCs, there is often only one external serial port as mice use a separate PS/2 port, and modems are generally built in and use an internal serial port. The term originated before the days of the mouse, when the serial port was primarily used for modem COM-munications.

Stands for "Read-Only Memory." Please do not confuse this term with RAM or a hard drive, as many people already do. ROM is memory containing hardwired instructions that the computer uses when it boots up, before the system software loads. In PCs, the instructions are read from a small program in the ROM, called the BIOS (Basic Input/Output System).

Stands for "Network Interface Card." Pronounced "nick," this is the card that physically makes the connection between the computer and the network cable. These cards typically use an Ethernet connection and are available in 10, 100, and 1000 Base-T configurations. A 100 Base-T card can transfer data at 100 Mbps. The cards come in ISA and PCI versions and are made by companies like 3Com and LinkSys.

Radio frequency, or RF, is a frequency or rate of oscillation within the range of about 3 Hz and 30 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves. Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits.

File Allocation Table (FAT) is a partially patented file system developed by Microsoft for MS-DOS and was the primary file system for consumer versions of Microsoft Windows up to and including Windows Me. FAT as it applies to flexible/floppy and optical disk cartridges (FAT12 and FAT16 without long file name support) has been standardized as ECMA-107 and ISO/IEC 9293. The FAT file system is relatively uncomplicated, and is supported by virtually all existing operating systems for personal computers. This ubiquity makes it an ideal format for floppy disks and solid-state memory cards, and a convenient way of sharing data between disparate operating systems installed on the same computer (a dual boot environment).

Stands for "New Technology File System." NTFS is a file system introduced by Microsoft with Windows NT and is supported by subsequent versions of Windows, such as Windows 2000 and Windows XP. (The file system is how the operating system organizes and accesses files on the hard drive.) NTFS has a number of advantages over the older file system, named FAT, or file allocation table. One major advantage of NTFS is that it incorporates features to improve reliablity. For exmaple, the new technology file system includes fault tolerance, which repairs hard drive errors without displaying error messages. It keeps detailed transaction logs, which tracks hard drive errors. This can help prevent hard disk failure as well as make it possible to recover files if the hard drive does fail. NTFS also allows permissions (such as read, write, and execute) to be set for individual directories and files. It even supports spanning volumes, which allows directories of files to be spread across multiple hard drives. The only reason why you would not want to select NTFS when formatting your hard drive is if you like slow, outdated technology or you need to run an older operating system such as Windows 95 or MS-DOS. Of course, if you are running DOS, there is a good chance you really do like outdated technology.

Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means "below red" (from the Latin infra, "below"), red being the color of visible light with the longest wavelength. Infrared radiation has wavelengths between about 750 nm and 1 mm, spanning three orders of magnitude.

The word modem is actually short for Modulator/Demodulator. (There's something you can really impress your friends with). A modem is a communications device that can be either internal or external to your computer. It allows one computer to connect another computer and transfer data over telephone lines. The original dial-up modems are becoming obsolete because of their slow speeds and are being replaced by the much faster cable and DSL modems.

Also known as an "OS," this is the software that communicates with computer hardware on the most basic level. Without an operating system, no software programs can run. The OS is what allocates memory, processes tasks, accesses disks and peripherials, and serves as the user interface. Thanks to operating systems, like Windows, Mac OS, and Linux, developers can write code using a standard programming interface, or API. Without an operating system, programmers would have to write about ten times as much code to get the same results. Of course, some computer geniuses have to program the operating system itself.

This term usually refers to the person behind the wheel of a moving car. In the computer world, however, a driver is a small file that helps the computer communicates with a certain hardware device. It contains information the computer needs to recognize and control the device. In Windows-based PCs, a driver is often packaged as a dynamic link library, or .dll file. In Macs, most hardware devices don't need drivers, but the ones that do usually come with a software driver in the form of a system extension, or .kext file.

Computer programming is a complicated and time-consuming task. Therefore, software development programs aim to make the development process as smooth as possible. IDE programs include a source code editor, compiler, and usually a debugger that all work together when building a software program. The IDE keeps track of all files related to a project and provides a central interface for writing source code, linking files together, and debugging the software. IDE programming software may also include a runtime environment (RTE) for testing the software. When a program is run within the RTE, the software can track each event that takes place within the application being tested. This can be an invaluable tool for debugging the program. Because the IDE software uses a central interface for writing the code and testing the program, it is easy to make quick changes to the code, recompile it, and run the program again. Programming is still hard work, but IDE software helps make the processes a little more trouble-free.

Memory is hardware that your computer uses to load the operating system and run programs. It consists of one or more RAM chips that each have several memory modules. The amount of real memory in a computer is limited to the amount of RAM installed. Common memory sizes are 256MB, 512MB, and 1GB. Because your computer has a finite amount of RAM, it is possible to run out of memory when too many programs are running at one time. This is where virtual memory comes in. Virtual memory increases the available memory your computer has by enlarging the "address space," or places in memory where data can be stored. It does this by using hard disk space for additional memory allocation. However, since the hard drive is much slower than the RAM, data stored in virtual memory must be mapped back to real memory in order to be used. The process of mapping data back and forth between the hard drive and the RAM takes longer than accessing it directly from the memory. This means that the more virtual memory is used, the more it will slow your computer down. While virtual memory enables your computer to run more programs than it could otherwise, it is best to have as much physical memory as possible. This allows your computer to run most programs directly from the RAM, avoiding the need to use virtual memory. Having more RAM means your computer works less, making it a faster, happier machine.

Fragmentation is a phenomenon that leads to inefficiency in many forms of computer storage. There are three different but related uses of the term: external fragmentation, internal fragmentation, and data fragmentation. Various storage allocation schemes exhibit one or more of these weaknesses, which have the effect of reducing storage capacity.

In computer science, a virtual machine is software that creates a virtualized environment between the computer platform and its operating system, so that the end user can operate software on an abstract machine.

Binary is a two-digit (Base-2) numerical system, which computers use to store data and compute functions. The reason computers use the binary system is because digital switches inside the computer can only be set to either on or off, which are represented by a 1 or 0. Though the binary system consists of only ones and zeros, the two digits can be used to represent any number.

Hexadecimal is a base-16 number system. It is a different method of representing numbers than the base-10 system we use in every day practice. In base-10, we count in multiples of 10 before adding another digit. For example, "8 - 9 - 10 - 11 - 12..." and "98 - 99 - 100 - 101 - 102..." Notice how a new digit is added when the number 10 is reached, and another digit is added to represent 100 (10x10). In base-16, or the hexadecimal number system, each digit can have sixteen values instead of ten. The values of a hexadecimal digit can be: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F Therefore, the number 12 (in the common base-10 format) would be represented as "C" in hexadecimal notation. The number 24 would be 18 (16+8). 100 is 64 in hexadecimal (16x6 + 4) and 1000 is 3E8 (256x3 + 16x14 + 8). While computers process numbers using the base-2, or binary system, it is often more efficient to visually represent the numbers in hexadecimal format. This is because it only takes one hexadecimal digit to represent four binary digits. Since there are eight binary digits in a byte, only two hexadecimal digits are needed to represent one byte.

In computing, an octet is a grouping of eight bits. In France, French Canada and Romania, the word octet usually means byte; a megabyte (MB) is called a megaoctet in France, Romania and also French Canada. Bit and Byte are homophones in the French language. Octet, with the only exception noted below, always refers to an entity having exactly eight bits. As such, it is often used where the term byte might be ambiguous. For that reason, computer networking standards almost exclusively use octet.

Stands for "American Standard Code for Information Interchange." ASCII is the universal standard for the numerical codes computers use to represent all upper and lower-case letters, numbers, and puctuation. Without ASCII, each type of computer would use a different way of representing letters and numbers, causing major chaos for computer programmers (allowing them even less sleep than they already get). ASCII makes is possible for text to be represented the same way on a Dell Dimension in Minneapolis, Minnesota as it is on an Apple Power Mac in Paris, France. There are 128 standard ASCII codes, each of which can be represented by a 7 digit binary number (because 2^7 = 128).

Stands for "Uniform Resource Locator." A URL is the address of a specific Web site or file on the Internet.

A compact string of characters used to identify or name a resource. The main purpose of this identification is to enable interaction with representations of the resource over a network, typically the World Wide Web, using specific protocols. URIs are defined in schemes defining a specific syntax and associated protocols.

A slash or stroke is a punctuation mark. It is also called an oblique, diagonal, separatrix, virgule, scratch comma, slant, or forward slash.

First introduced in 1960 by Bob Bemer, the backslash, \, is a typographical mark (glyph) used chiefly in computing. Sometimes called a reverse solidus, it is the mirror image of the common slash.

The at sign (@, read aloud in English as "at") is a typographic symbol used as an abbreviation for "at" in accounting and commercial invoices, in statements such as "7 widgets @ $2 ea. = $14". More recently, the at symbol has become ubiquitous because of its use in e-mail addresses. It is often referred to informally as the at symbol, the at sign, or just at. In other languages, the symbol may have a different name (see below). It has the official name commercial at in the ANSI/CCITT/Unicode character encoding standards. However, no formal English term has been officially assigned to this character.

An ampersand (&), also commonly called an "and sign" is a logogram representing the conjunction "and." The symbol is a ligature of the letters in et, Latin for "and."

In Unix shells, the tilde indicates the current user's home directory (e.g., /home/username). When prepended to a particular username, it indicates that user's home directory (e.g., ~janedoe for the home directory of user janedoe, typically /home/janedoe). When some Unix shell commands overwrite a file, they can be made to keep a backup by renaming the original file as filename~. Used in URLs on the World Wide Web, it often denotes a personal website on a Unix-based server. For example, http://www.example.com/~johndoe/ might be the personal web site of John Doe. This mimics the Unix shell usage of the tilde. However, when accessed from the web, file access is usually directed to a subdirectory in the user's home directory, such as /home/username/public_html or /home/username/www. In URLs, the characters %7E (or %7e) may substitute a tilde if an input device lacks a tilde key. Thus, http://www.example.com/~johndoe/ and http://www.example.com/%7Ejohndoe/ are essentially the same URL.

Phishing is similar to fishing in a lake, but instead of trying to capture fish, phishers attempt to steal your personal information. They send out e-mails that appear to come from legitimate websites such as eBay, PayPal, or other banking institutions. The e-mails state that your information needs to be updated or validated and ask that you enter your username and password, after clicking a link included in the e-mail. Some e-mails will ask that you enter even more information, such as your full name, address, phone number, social security number, and credit card number. However, even if you visit the false website and just enter your username and password, the phisher may be able to gain access to more information by just logging in to you account. Phishing is a con game that scammers use to collect personal information from unsuspecting users. The false e-mails often look surprisingly legitimate, and even the Web pages where you are asked to enter your information may look real. However, the URL in the address field can tell you if the page you have been directed to is valid or not. For example, if you are visiting an Web page on eBay, the last part of the domain name should end with "ebay.com." Therefore, "http://www.ebay.com" and "http://cgi3.ebay.com" are valid Web addresses, but "http://www.ebay.validate-info.com" and "http://ebay.login123.com" are false addresses, which may be used by phishers. If URL contains an IP address, such as 12.30.229.107, instead of a domain name, you can almost be sure someone is trying to phish for your personal information. If you receive an e-mail that asks that you update your information and you think it might be valid, go to the website by typing the URL in your browser's address field instead of clicking the link in the e-mail. For example, go to "https://www.paypal.com" instead of clicking the link in an e-mail that appears to come from PayPal. If you are prompted to update your information after you have manually typed in the Web address and logged in, then the e-mail was probably legitimate. However, if you are not asked to update any information, then the e-mail was most likely a spoof sent by a phisher. Most legitimate e-mails will address you by your full name at the beginning of the message. If there is any doubt that the e-mail is legitimate, be smart and don't enter your information. Even if you believe the message is valid, following the guidelines above will prevent you from giving phishers your personal information.

Just like regular worms tunnel through dirt and soil, computer worms tunnel through your computer's memory and hard drive. A computer worm is a type of virus that replicates itself, but does not alter any files on your machine. However, worms can still cause havoc by multiplying so many times that they take up all your computer's available memory or hard disk space. If a worm consumes your memory, your computer will run very slowly and possibly even crash. If the worm affects your hard disk space, your computer will take a long time to access files and you will not be able to save or create new files until the worm has been eradicated. Worms are hard to detect because they are typically invisible files. They often go unnoticed until your computer begins to slow down or starts having other problems. Unlike viruses and Trojan horses, worms can replicate themselves and travel between systems without any action from the user. For these reasons, it is good to have an antivirus program installed on your system that can detect and remove worms before they have a chance to replicate or spread to other computers. Security updates such as Windows Update also patch security holes that allow worms to infect your computer. So keep your security updates and virus definitions up-to-date and you should be able to keep your computer worm-free.

Stands for "Virtual Private Network." This is a network term that most computer users don't need to know, but at least you can impress your friends by talking about it. A VPN refers to a network that is connected to the Internet, but uses encryption to scramble all the data sent through the Internet so the entire network is "virtually" private. For example, a large company that has offices in multiple locations may need to send data to the different locations via the Internet. To keep the information secure, the company might first set up a VPN with an encrypted connection. It's basically like having a secure Intranet over the Internet.

Pretty Good Privacy is a computer program that provides cryptographic privacy and authentication. PGP encryption uses public-key cryptography and includes a system which binds the public keys to a user name. The first version of this system was generally known as a web of trust to contrast with the X.509 system which uses a hierarchical approach based on certificate authority and which was added to PGP implementations later. Current versions of PGP encryption include both alternatives through an automated key management server.

An information audit trail or information audit log is a chronological sequence of audit records, each of which contains data about when and by whom was a particular record changed. It can also include information about the actual changes that were made. It can enable the reconstruction and examination of the end states of data, and reconstruct the intermediate states that the data went through before the final state was established.

The degree to which a system, subsystem, or equipment is operable and in a committable state at the start of a mission, when the mission is called for at an unknown, i.e., a random, time. Simply put, availability is the proportion of time a system is in a functioning condition.

In computer security and programming, a buffer overflow, or buffer overrun, is a programming error which may result in a memory access exception and program termination, or in the event of the user being malicious, a possible breach of system security. A buffer overflow is an anomalous condition where a process attempts to store data beyond the boundaries of a fixed-length buffer. The result is that the extra data overwrites adjacent memory locations. The overwritten data may include other buffers, variables and program flow data and may cause a process to crash or produce incorrect results. They can be triggered by inputs specifically designed to execute malicious code or to make the program operate in an unintended way. As such, buffer overflows cause many software vulnerabilities and form the basis of many exploits. Sufficient bounds checking by either the programmer, the compiler or the runtime can prevent buffer overflows.

A logic bomb is a piece of code intentionally inserted into a software system that will set off a malicious function when specified conditions are met. For example, a programmer may hide a piece of code that starts deleting files (such as the salary database), should they ever leave the company. Software that is inherently malicious, such as viruses and worms, often contain logic bombs that execute a certain payload at a pre-defined time or when some other condition is met. This technique can be used by a virus or worm to gain momentum and spread before being noticed. Many viruses attack their host systems on specific dates, such as Friday the 13th or April Fool's Day. Trojans that activate on certain dates are often called "time bombs". To be considered a logic bomb, the payload should be unwanted and unknown to the user of the software. As an example, trial programs with code that disables certain functionality after a set time are not normally regarded as logic bombs.

Social engineering is a collection of techniques used to manipulate people into performing actions or divulging confidential information. While similar to a confidence trick or simple fraud, the term typically applies to trickery for information gathering or computer system access and in most cases the attacker never comes face-to-face with the victim.

The term password strength is a security measure of passwords. The necessary quality of the password depends on how well the password system limits attempts to guess a user's password, whether by a person who knows the user well, or a computer trying millions of possibilities. In a cryptographic context, the terms can have considerable precision. For example, passwords generally are not suitable for use as encryption keys. However, note that even a 'strong' password may still be stolen, tricked, or extorted from a user, collected from a keyboard logger, intercepted in transit, or otherwise discovered by another person.

Confidentiality has been defined by the International Organization for Standardization (ISO) as "ensuring that information is accessible only to those authorized to have access" and is one of the cornerstones of Information security. Confidentiality is one of the design goals for many cryptosystems, made possible in practice by the techniques of modern cryptography.

In computer security, authentication is the process of attempting to verify the digital identity of the sender of a communication such as a request to log in. The sender being authenticated, often referred to as the principal, may be a person using a computer, a computer itself or a computer program. A blind credential, in contrast, does not establish identity at all, but only a narrow right or status of the user or program. In a web of trust, "authentication" is a way to ensure users are who they say they are—that the user who attempts to perform functions in a system is in fact the user who is authorized to do so.

Like a biological virus, a computer virus is something you don't want to get. Computer viruses are small programs or scripts that can negatively affect the health of your computer. These malicious little programs can create files, move files, erase files, consume your computer's memory, and cause your computer not to function correctly. Some viruses can duplicate themselves, attach themselves to programs, and travel across networks. In fact opening an infected e-mail attachment is the most common way to get a virus. We all know it's hard enough to get a computer to work well when it is healthy, let alone when it has been attacked by a virus. Therefore, it is better to prevent an attack than to try and cure it. There are many anti-virus programs available that scan incoming files for viruses before they can cause damage to your computer. Some of these programs include Norton AntiVirus®, McAfee VirusScan®, and Virex®. It is a good idea to have one of these programs on your computer to prevent a virus attack. It is also important to update your virus definitions file at least once a month so that your anti-virus program can check for all the latest viruses. It's a lot like having a glass of orange juice every morning -- it keeps your computer's immune system strong and healthy.

While the term "firewall" creates a powerful visual picture, in reality, it doesn't involve any fire or pyrotechnics. A computer firewall is used to protect a networked server or client machine from damage by unauthorized users. The firewall can be either hardware or software-based. A router is a good example of a hardware device that often has a built-in firewall. Software programs that monitor and restrict external access to a computer can also serve as firewalls. A network firewall allows only certain messages from the Internet to flow in and out of the network. So, I guess in a way it really is like a wall of fire. Well, sort of.

Originating from the name of Hormel's canned meat, "spam" now also refers to junk e-mail or irrelevant postings to a newsgroup or bulletin board. The unsolicited e-mail messages you receive about refinancing your home, reversing aging, and losing those extra pounds are all considered to be spam. Spamming other people is definitely not cool and is one of the most notorious violations of Internet etiquette (or "netiquette"). So if you ever get the urge to let thousands of people know about that hot new guaranteed way to make money on the Internet, please reconsider.

In cryptography, a public key infrastructure (PKI) is an arrangement that binds public keys with respective user identities by means of a certificate authority (CA). The user identity must be unique for each CA. This is carried out by software at a CA, possibly under human supervision, together with other coordinated software at distributed locations. For each user, the user identity, the public key, their binding, validity conditions and other attributes are made unforgeable in public key certificates issued by the CA.

An online internet filter.

Encryption is the coding or scrambling of information so that it can only be decoded and read by someone who has the correct decoding key. Encryption is used in secure Web sites as well as other mediums of data transfer. If a third party were to intercept the information you sent via an encrypted connection, they would not be able to read it. So if you are sending a message over the office network to your co-worker about how much you hate your job, your boss, and the whole dang company, it would be a good idea to make sure that you send it over an encrypted line.

Short for Concurrent Versions System, an open-source, network-transparent program that allows developers to keep track of different development versions of source code. CVS does not maintain multiple versions of source code files but keeps a single copy and records of all of the changes that are made. When a developer wants a particular development version of a file, CVS will reconstruct that version based on its records.

In a P2P network, the "peers" are computer systems which are connected to each other via the Internet. Files can be shared directly between systems on the network without the need of a central server. In other words, each computer on a P2P network becomes a file server as well as a client. The only requirements for a computer to join a peer-to-peer network are an Internet connection and P2P software. Common P2P software programs include Kazaa, Limewire, BearShare, Morpheus, and Acquisition. These programs connect to a P2P network, such as "Gnutella," which allows the computer to access thousands of other systems on the network. Once connected to the network, P2P software allows you to search for files on other people's computers. Meanwhile, other users on the network can search for files on your computer, but typically only within a single folder that you have designated to share. While P2P networking makes file sharing easy and convenient, is also has led to a lot of software piracy and illegal music downloads. Therefore, it is best to be on the safe side and only download software and music from legitimate websites.

Stands for "File Transfer Protocol." It is a common method of transferring files via the Internet from one computer to another. Some common FTP programs are "Fetch" for the Mac, and "WS_FTP" for Windows. However, you can also use a Web browser like Netscape or Internet Explorer to access FTP servers. To do this, you need to type the URL of the server into the location field of the browser. For example: "ftp://ftp.servername.com/" will give you a listing of all the directories of the FTP server, "ftp://ftp.servername.com/directory/" will give you a listing of all the files available in that directory, and "ftp://ftp.servername.com/directory/filename" will download the actual file to your computer. Many FTP servers are "anonymous FTP" servers which means you can log in with the user name "anonymous" and your e-mail address as the password. Other FTP servers require a specific login in order to access the files.

This refers to high-speed data transmission in which a single cable can carry a large amount of data at once. The most common types of Internet broadband connections are cable modems (which use the same connection as cable TV) and DSL modems (which use your existing phone line). Because of its multiple channel capacity, broadband has started to replace baseband, the single-channel technology originally used in most computer networks.

BitTorrent is a peer-to-peer (P2P) file sharing protocol designed to reduce the bandwidth required to transfer files. It does this by distributing file transfers across multiple systems, thereby lessening the average bandwidth used by each computer. For example, if a user begins downloading a movie file, the BitTorrent system will locate multiple computers with the same file and begin downloading the file from several computers at once. Since most ISPs offer much faster download speeds than upload speeds, downloading from multiple computers can significantly increase the file transfer rate. In order to use the BitTorrent protocol, you need a BitTorrent client, which is a software program that accesses the BitTorrent network. The client program allows you to search for files and begin downloading torrents, which are in-progress downloads. Most BitTorrent clients allow you to resume torrents that have been paused or stopped. This can be especially helpful when downloading large files.

A computer or device on a network that manages network resources. For example, a file server is a computer and storage device dedicated to storing files. Any user on the network can store files on the server. A print server is a computer that manages one or more printers, and a network server is a computer that manages network traffic. A database server is a computer system that processes database queries. Servers are often dedicated, meaning that they perform no other tasks besides their server tasks. On multiprocessing operating systems, however, a single computer can execute several programs at once. A server in this case could refer to the program that is managing resources rather than the entire computer.

Stands for "Local Area Network," and is pronounced like "land" without the "d". (Computer people will think you're weird if you pronouce it "L-A-N"). A LAN is a computer network limited to a small area such as an office building, university, or even a residential home. Most mid to large-sized businesses today use LANs, which makes it easy for employees to share information. Currently, the most common type of LANs are Ethernet-based and use software from Novell or Oracle. However, with the emergence of wireless networking, wireless LANs have become a popular alternative.

Ethernet is the most common type of connection computers use in a local area network (LAN). An Ethernet port looks much like a regular phone jack, but it is slightly wider. This port can be used to connect your computer to another computer, a local network, or an external DSL or cable modem. Two widely-used forms of Ethernet are 10BaseT and 100BaseT. In a 10BaseT Ethernet connection, data transfer speeds can reach 10 mbps (megabits per second) through a copper cable. In a 100BaseT Ethernet connection, transfer speeds can get up to 100 mbps.

National LambdaRail is a high-speed national computer network in the United States that runs over fiber-optic lines, and is the first transcontinental Ethernet network. The name is shared by the organization of research institutions that developed the network, and, to date, plans to continue developing it. LambdaRail is similar to the Abilene Network, but LambdaRail permits deeper experimentation than Abilene does. It is primarily oriented to aid terascale computing efforts, but is also not intended to be a service network, but to be used as a network testbed for experimentation with next-generation large-scale networks. National LambdaRail is a university-based and -owned initiative, in contrast with Abilene and Internet2, which are university-corporate sponsorships. This gives universities more control to use the network for these research projects. Links in the network use dense wavelength-division multiplexing (DWDM), which allows up to 32 or 40 individual optical wavelengths to be used (depending on hardware configuration at each end). At present, individual wavelengths are used to carry a 10-gigabit Ethernet signal, although other systems such as SONET may also be used in the future.

When computers communicate with each other, there needs to be a common set of rules and instructions that each computer follows. A specific set of communication rules is called a protocol. Because of the many ways computers can communicate with each other, there are many different protocols -- too many for the average person to remember. Some examples of these different protocols include PPP, TCP/IP, SLIP, HTTP, and FTP.

Stands for "Transmission Control Protocol/Internet Protocol." These two protocols were developed in the early days of the Internet by the U.S. military. The purpose was to allow computers to communicate over long distance networks. The TCP part has to do with the verifying delivery of the packets. The IP part refers to the moving of data packets between nodes. TCP/IP has since then become the foundation of the Internet. Therefore, TCP/IP software is built into all major operating systems, such as Unix, Windows, and the Mac OS.

A network architecture in which each computer or process on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers ). Clients are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power.

Just like the human backbone carries signals to many smaller nerves in the body, a network backbone carries data to smaller lines of transmission. A local backbone refers to the main network lines that connect several local area networks (LANs) together. The result is a wide area network (WAN) linked by a backbone connection. The Internet, which is the ultimate wide area network, relies on a backbone to carry data over long distances. The Internet backbone consists of several ultra-high bandwidth connections that link together many different nodes around the world. These nodes route incoming data to smaller networks in the local region. The fewer "hops" your data needs to make before reaching the backbone, the faster it will get sent to the destination. This is why many Web hosts and ISPs have direct connections to the Internet backbone.

This is a hardware device that is used to network multiple computers together. It is a central connection for all the computers in a network, which is usually Ethernet-based. Information sent to the hub can flow to any other computer on the network. If you need to connect more than two computers together, a hub will allow you to do so. If you only need to network two computers together, a simple crossover Ethernet cable will do the trick.

This is a hardware device that routes data (hence the name) from a local area network (LAN) to another network connection. A router acts like a coin sorting machine, allowing only authorized machines to connect to other computer systems. Most routers also keep log files about the local network activity.

A switch is used to network multiple computers together. Switches made for the consumer market are typically small, flat boxes with 4 to 8 Ethernet ports. These ports can connect to computers, cable or DSL modems, and other switches. High-end switches can have more than 50 ports and often are rack mounted. Switches are more advanced than hubs and less capable than routers. Unlike hubs, switches can limit the traffic to and from each port so that each device connected to the switch has a sufficient amount of bandwidth. For this reason, you can think of a switch as a "smart hub." However, switches don't provide the firewall and logging capabilities that routers do. Routers can often be configured by software (typically via a Web interface), while switches only work the way the hardware was designed. The term "switch" can also be used to refer to a small lever or button on computer hardware.

As the name implies, a server serves information to computers that connect to it. When users connect to a server, they can access programs, files, and other information from the server. Common servers are Web servers, mail servers, and LAN servers. A single computer can have several different server programs running on it.

IEEE 802.11g-1999 or 802.11g, is an amendment to the IEEE 802.11 specification that extended throughput to up to 54 Mbit/s using the same 2.4 GHz band. This specification under the marketing name of Wi-Fi has been implemented all over the world. The amendment has been incorporated into the published IEEE 802.11-2007 standard. 802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, and 802.11g versions to provide wireless connectivity in the home, office and some commercial establishments.

Stands for "Domain Name System." The primary purpose of DNS is to keep Web surfers sane. Without DNS, we would have to remember the IP address of every site we wanted to visit, instead of just the domain name. Can you imagine having to remember "17.254.3.183" instead of just "apple.com"? While I have some Computer Science friends who might prefer this, most people have an easier time remembering simple names. The reason the Domain Name System is used is because Web sites are acutally located by their IP addresses. For example, when you type in "http://www.adobe.com," the computer doesn't immediately know that it should look for Adobe's Web site. Instead, it sends a request to the nearest DNS server, which finds the correct IP address for "adobe.com." Your computer then attempts to connect to the server with that IP number. DNS is just another one of the many features of the Internet that we take for granted.

Stands for "Internet Service Provider." In order to connect to the Internet, you need an ISP. It is the company that you (or your parents) pay a monthly fee to in order to use the Internet. If you use a dial-up modem to connect to your ISP, a point-to-point protocol (PPP) connection is established with another modem on the ISP's end. That modem connects to one of the ISP's routers, which routes you to the Internet "backbone." From there, you can access information from anywhere around the world. DSL and cable modems work the same way, except after you connect the first time, you are always connected.

Abbreviated as ASP, a specification for a dynamically created Web page with a .ASP extension that utilizes ActiveX scripting -- usually VB Script or Jscript code. When a browser requests an ASP, the Web server generates a page with HTML code and sends it back to the browser. So ASPs are similar to CGI scripts, but they enable Visual Basic programmers to work with familiar tools.

Used typically in reference to a computer language to mean a command or statement in the language that is going to be made invalid or obsolete in future versions.

A web page, as an information set, can contain many kinds of information, which is able to be seen, heard or interact by the end user. These are the elements.

Verification that something is correct or conforms to a certain standard. In data collection or data entry, it is the process of ensuring that the data that are entered fall within the accepted boundaries of the application collecting the data. For example, if a program is collecting last names to be entered in a database, the program validates that only letters are entered and not numbers; or in a survey collecting data in the form of “yes” or “no” questions, the program validates that only those responses are used and not some other word. Validation procedures typically are written into the program code and are therefore invisible to the user.

One of the three HTML 4.0 DTDs. Use this DTD when you want to use frames!

One of the three HTML 4.0 DTDs. Use this when you want clean markup, free of presentational clutter. Use this together with Cascading Style Sheets (CSS).

One of the three HTML 4.0 DTDs. Use this DTD when you need to use XHTML's presentational features because your readers don't have browsers that support Cascading Style Sheets (CSS).

A language construct that programmers use to add additional information (i.e., metadata) to code elements (e.g., assemblies, modules, members, types, return values, and parameters) to extend their functionality.

In programming, syntactic elements of a programming language. For example, it can be the way in which an HTML tag, or more commonly an XML element, may be used; see well-formed element.

Short for document type definition. A DTD states what tags and attributes are used to describe content in an SGML, XML or HTML document, where each tag is allowed, and which tags can appear within other tags. For example, in a DTD one could say that LIST tags can contain ITEM tags, but ITEM tags cannot contain LIST tags. In some editors, when authors are inputting information, they can place tags only where the DTD allows. This ensures that all the documentation is formatted the same way. Applications will use a document's DTD to properly read and display a document's contents. Changes in the format of the document can be easily made by modifying the DTD.

Short for Cascading Style Sheets, a new feature being added to HTML that gives both Web site developers and users more control over how pages are displayed. With CSS, designers and users can create style sheets that define how different elements, such as headers and links, appear. These style sheets can then be applied to any Web page. The term cascading derives from the fact that multiple style sheets can be applied to the same Web page. CSS was developed by the W3C.

Short for World Wide Web Consortium, an international consortium of companies involved with the Internet and the Web. The W3C was founded in 1994 by Tim Berners-Lee, the original architect of the World Wide Web. The organization's purpose is to develop open standards so that the Web evolves in a single direction rather than being splintered among competing factions.